Trichloroacetic acid dichloroethylidene hydrazide and process therefor



United States Patent 3,306,935 TRICHLOROACETIC ACID DICHLOROETHYLI- DENEHYDRAZIDE AND PROCESS THEREFOR Christ N. Yiannios, North Haven, andJoseph V. Karabinos, Orange, Conn, assignors to Olin Mathieson ChemicalCorporation, New Haven, (301111., a corporation of Virginia No Drawing.Filed July 30, 1965, Ser. No. 476,150 4 Claims. (Cl. 260-561) Thisinvention relates to a novel substituted hydrazide, and morespecifically it relates to trichloroacetic acid dichloroethylidenehydrazide having the formula:

It has been found that the heretofore unknown hydrazide I can beprovided in high yield and purity by the reaction of chloral withhydrazine under anhydrous conditions and in the presence of selectedcarboxylic acids. The preparation of the hydrazide I is believed toproceed according to the following reaction scheme wherein achloralhydrazine intermediate II is first formed.

II RCOOH ClaCCHO The preparation of trichloroacetic aciddichloroethylidene hydrazide in accordance with the process disclosedherein is a surprising and unexpected feature of this invention. Thereaction of chloral with hydradine has been previously reported, andthere is no suggestion that the compound I is provided as a product. Forinstance, Knopfer in Monatshefte fur chemie, 37, 364 (1916) hasdisclosed that hydrazine hydrate and chloral hydrate react in glacialacetic acid to provide a five membered heterocyclic compound having twonitrogen atoms in the ring system and six chlorine atoms.

As mentioned in the foregoing discussion, a selected carboxylic acidmust be utilized in the process of this invention. The function of thisacid is not completely understood, but it apparently reacts with thebasic chloralhydrazine prior to the further reaction of a second mole ofchloral wherein hydrazide I formation is completed. Thusstoichiometrically the process requires the use of an equimolar amountof the acid relative to the amount of formed chloralhydrazine II. It hasbeen found that carboxylic acids having 1-4 carbon atoms and adissociation constant of at least 1.0x l0 in water at 25 C. can besuccessfully utilized in the preparation of the hydrazide I.Particularly useful in this regard are the fatfiy acids such as formic,acetic, propionic and butyric act 5.

The formation of trichloroacetic acid dichloroethylidene hydrazide fromthe chloralhydrazine intermediate proceeds at a temperature range ofabout 25 C. to about 80 C. and most advantageously at 40-60 C. Thusgenerally the process of this invention comprises contacting hydrazine,chloral and the selected carboxylic carboxylic acid together at theaforementioned temperature range to provide the hydrazide I. It isadvantageous to utilize an excess amount of carboxylic acid wherein italso functions as a diluent to enhance hydrazide yield, but this is notan essential feature of the process disclosed herein. Upon completion ofthe reaction, some of the desired hydrazide is obtained immediately inthe form of a precipitated solid with the amount depending essentiallyupon the amount of carboxylic acid diluent employed. The remainder ofthe desired product is conveniently provided by pouring the reactionmixture into ice water wherein the insoluble trichloroacetic aciddichloroethylidene hydrazide is separated by filtration, centrifugationor similar procedures.

However, the preferred process embodiment comprises formingchloralhydrazine II by reaction of substantially equimolar quantities ofchloral and hydrazine prior to introduction of the carboxylic acid andadditional chloral into the reaction system. The chloral and hydrazineare conveniently reacted together in an inert diluent such as ether,petroleum ether, benzene, toluene, etc., to provide a solution of thechloralhydrazine. Preferably intermediate II formation is accomplishedbelow 25 C. to minimize degradation of this compound. Then thecarbox-ylic acid and additional chloral required to complete thehydrazide preparation are added to the chloralhydrazine solution, andhydrazide I is formed at about 25 C. to about C. Volatile solvents suchas ether and petroleum ether can be removed by distillation in thistemperature range leaving a reaction mixture which can be treated asdisclosed in the foregoing discussion to isolate the desired compound I.When higher boiling solvents such as benzene and toluene are employed,workup is accomplished by pouring the entire reaction mixture into waterwherein a two layer system is achieved. The hydrazide is essentiallyinsoluble in water and preferably soluble in benzene or toluene thusaffording a ready method of separation upon evaporation of solvent. Thehydrazide can 'be recrystallized from solvents such as benzene, tolueneand preferably xylenes.

Trichloroacetic acid dichloroethylidene hydrazide is a usefulagricultural chemical and has demonstrated utility as a nematocideespecially in the control of the root knot nematode. It is particularlyvaluable as a preplant herbicide wherein it is incorporated in the soilsurrounding valuable crops before the crop is planted or simultaneouslywith the crop planting. Thus, when herbicidal formulations containingthe hydrazide I as the active ingredient are applied to the soil areasurrounding cotton and corn plants, outstanding control of variousharmful Weed species including pigweed, crabgrass, mustard, and ryegrasshas been obtained. It has been found that the hydrazide is effective inthis application in amounts of as little as 12 pounds per acre althoughgenerally it is utilized in amounts of 2-10 pounds per acre.

Although trichloroacetic acid dichloroethylidene hydrazide can beemployed in concentrated form as a herbicide, it is more practical toutilize it in a dispersed form admixed with a major amount of a suitablecarrier or diluent. A variety of liquid and solid diluents may beemployed in the preparation of useful herbicidal formulations containingthe hydrazide as the active ingredient. It is preferably applied to thesoil in the form of a dust or a powder wherein it is admixed with inertsolids such as kaolin, calcium carbonate, talc, Bardens clay, and thelike. Generally it is incorporated with such solid carriers as a resultof suitable ball milling or grinding operations. A suitable wetting ordispersing agent such as for instance an ethoxylated nonylphenol can beadded to these solid formulations to provide wettable powders which areespecially suitable for mixing with water to obtain dispersions usefulin spraying operations. The hydrazide I can also be applied to the soil'by spraying operations wherein solutions of the active ingredient inappropriate organic solvents are utilized.

The following example is illustrative of the preparation oftrichloroacetic acid dichloroethylidene hydrazide in accordance withthis invention.

Example 1 Into a three liter, three-necked flask equipped with airstirrer, dropping funnel, thermometer, water condenser and a nitrogeninlet tube was placed 147 g. (1.0 mole) of anhydrous chloral dissolvedin 900 ml. of absolute ether. The reaction fiask was immersed in asalt-ice bath, and the solution was cooled to 5 C. and blanketed with anitrogen atmosphere. While the etheral chloral solution was stiredvigorously, 32 g. (1.0 mole) of anhydrous hydrazine was added dropwiseat a rate such that the temperature in the flask was maintained between5 C. and 3 C. A white powder, the chloral-hydrazine adduct, startedprecipitating immediately. When the addition of hydrazine was complete,three moles of anhydrous chloral (441 g.) dissolved in 800 ml. ofglacial acetic acid were added cautiously and the mixture was stirredfor 15 minutes at 5 C. Most of the ether was removed under vacuum. Thetemperature was allowed to rise gradually to 45 -50 C. at atmosphericpressure while sweeping nitrogen through the flask to remove the tracesof ether. During the rise in temperature, a series of color changes wereobserved from yellow to pink-red to orange and back to yellow. Aftercomplete removal of the ether was accomplished, the slurry dissolved togive a clear amber solution. This was stirred at 45 -50 C. for 5 hours.The solution was then allowed to stand at 5 C. overnight. A whitecrystalline precipitate formed, was collected by filtration, washedthree to five times with water and dried under vacuum at 45 -50 C. Thisproduct had a melting point of 135 15 C. Yield: 45%. The filtrate wasadded with agitation to three liters of ice water to give a light yellowprecipitate which was subsequently washed with cold water. This materialhad a melting point of 115130 C. The yield of the combined crudeproducts was 86%. Repetitious recrystallization of either crude materialfrom xylene raised the melting point to 159 160 C. For analyticalpurposes, a sample of crystallized material was dissolved in Xylene andpassed through a silica-gel column. The eluate was allowed to stand andcrystals were obtained which had a melting point of 1601 61 C. Thefollowing analytical data revealed that trichloroacetic aciddichloroethylidene hydrazide had been obtained in high purity.

AnaZysis.Calcd. for C H CI N O: C, 17.58; H, 1.10; N, 10.60; Cl, 65.10.Found: C, 17.90; H, 1.10; N, 10.45; Cl, 64.50.

Infrared and nuclear magnetic resonance spectra also confirmed thattrichloroacetic acid dichloroethylidene hydrazide had been obtained inhigh purity.

What is claimed is:

1. Trichloroacetic acid dichloroethylidene hydrazide.

2. A process for preparing trichloroacetic acid dichloroethylidenehydrazide which comprises forming chloralhydrazine by the reaction ofsubstantially equimolar amounts of chloral and hydrazine, reacting saidchloralhydrazine with chloral and a liquid carboxylic acid at atemperature of about 25 C. to about 80 C., said carboxylic acid having14 carbon atoms and having a dissociation constant of at least 1.0 1O inwater at 25 C.

3. The process of claim 2 wherein acetic acid is employed as therequired carboxylic acid.

4. The process of claim 2 wherein a reaction temperature range of 60 C.is utilized.

No references cited.

ALEX MAZEL, Primary Examiner.

I. A. NARCAVAGE, Assistant Examiner.

1. TRICHLOROACETIC ACID DICHLOROETHYLIDENE HYDRAZIDE.
 2. A PROCESS FORPREPARING TRICHLOROACETIC ACID DICHLOROETHYLIDENE HYDRAZIDE WHICHCOMPRISES FORMING CHLORALHYDRAZINE BY THE REACTION OF SUBSTANTIALLYEQUIMOLAR AMOUNTS OF CHORAL AND HYDRAZINE, REACTING SAIDCHLORALHYDRAZINE WITH CHLORAL AND A LIQUID CARBOXYLIC ACID AT ATEMPERATURE OF ABOUT 25* C. TO ABOUT 80* C., SAID CARBOXYLIC ACID HAVING1-4 CARBON ATOMS AND HAVING A DISSOCIATION CONSTANT OF AT LEAST 1.0X10-5IN WATER AT 25* C.